import java.util.Scanner;

public class Main1014 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        double a=0;
        if (1 <= n && n <= 200) {

            for (int i = 1; i <= n; i++) {
                double b=1.0/i;
                a=a+b;
            }
            System.out.println(String.format("%.3f",a));
        }
    }
}